The present invention relates to a collimator, as well as an X-ray irradiator and an X-ray apparatus. Particularly, the invention is concerned with a collimator for restricting an irradiation range of X-ray, as well as an X-ray irradiator and an X-ray apparatus both provided with such a collimator.
In an X-ray irradiator there is used a collimator for restricting an irradiation range of X-ray. The collimator has an aperture permitting X-ray to pass therethrough and has a structure such that X-ray cannot pass through the collimator except through the aperture. With this structure, the irradiation range of X-ray can be adjusted.
A collimator having a variable aperture is provided with movable plate members, namely, blades having X-ray absorbability. As the blades there are used a pair of blades opposed to each other at respective end faces. The pair of blades are movable in directions opposite to each other in a plane parallel to their surfaces. For expanding the aperture, the pair of blades are moved in directions away from each other, while for narrowing the aperture, the blades are moved toward each other.
Two pairs of such blades are combined perpendicularly to each other to afford a collimator wherein the size of aperture can be changed in two directions perpendicular to each other. In such a collimator, by making all of the blades adjustable independently, it is possible to adjust not only the size of aperture but also a two-dimensional position thereof (see, for example, Patent Literature 1).
[Patent Literature 1] Japanese Published Unexamined Patent Application No. 2002-355242 (pages 2 to 3, FIGS. 1 to 2)
In the above collimator, in order to make all of the blades adjustable independently, it is necessary to use special blades and a drive mechanism for the blades.